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Prior real-world studies have shown that apixaban is associated with a reduced risk of stroke/systemic embolism (stroke/SE) and major bleeding versus warfarin. However, few studies evaluated the effectiveness and safety of apixaban according to its dosage, and most studies contained limited numbers of patients prescribed 2.5 mg twice-daily (BID) apixaban. Using pooled data from 4 American claims database sources, baseline characteristics and outcomes for patients prescribed 5 mg BID and 2.5 mg BID apixaban versus warfarin were compared. After 1:1 propensity-score matching, 31,827 5 mg BID apixaban-matched warfarin patients and 6600 2.5 mg BID apixaban-matched warfarin patients were identified. Patients prescribed 2.5 mg BID apixaban were older, had clinically more severe comorbidities, and were more likely to have a history of stroke and bleeding compared with 5 mg BID apixaban patients. Compared with warfarin, 5 mg BID apixaban was associated with a lower risk of stroke/SE (hazard ratio [HR]: 0.70, 95% confidence interval [CI]: 0.60-0.81) and major bleeding (HR: 0.59, 95% CI: 0.53-0.66). Compared with warfarin, 2.5 mg BID apixaban was also associated with a lower risk of stroke/SE (HR: 0.63, 95% CI: 0.49-0.81) and major bleeding (HR: 0.59, 95% CI: 0.49-0.71). In this real-world study, both apixaban doses were assessed in 2 patient groups differing in age and clinical characteristics. Each apixaban dose was associated with a lower risk of stroke/SE and major bleeding compared with warfarin in the distinct population for which it is being prescribed in United States clinical practice.Clinicaltrials.Gov Identifier: NCT03087487.

The development of an effective malaria vaccine is a high global health priority. Vaccine vectors based on adenovirus type 5 are capable of generating robust and protective T cell and antibody responses in animal models and are currently being evaluated in clinical trials for HIV and malaria. They appear to be more effective in terms of inducing antigen-specific immune responses as compared with non-Ad5 serotype vectors. However, the high prevalence of neutralizing antibodies to Ad5 in the human population, particularly in the developing world, has the potential to limit the effectiveness of Ad5-based vaccines. We have generated novel Ad5-based vectors that precisely replace the hexon hypervariable regions with those derived from Ad43, a subgroup D serotype with low prevalence of neutralizing antibody in humans. We have demonstrated that these hexon-modified adenovectors are not neutralized efficiently by Ad5 neutralizing antibodies in vitro using sera from mice, rabbits and human volunteers. We have also generated hexon-modified adenovectors that express a rodent malaria parasite antigen, PyCSP, and demonstrated that they are as immunogenic as an unmodified vector. Furthermore, in contrast to the unmodified vector, the hexon-modified adenovectors induced robust T cell responses in mice with high levels of Ad5 neutralizing antibody. We also show that the hexon-modified vector can be combined with unmodified Ad5 vector in prime-boost regimens to induce protective responses in mice. Our data establish that these hexon-modified vectors are highly immunogenic even in the presence of pre-existing anti-adenovirus antibodies. These hexon-modified adenovectors may have advantages in sub-Saharan Africa where there is a high prevalence of Ad5 neutralizing antibody in the population.